Comment by rodalpho

I'm pasting it here as they typically delete the beta forums after release.

Metamorphosis leech reduced by 60% in PvP

Comment by Shadow12000

It seems Metamorphosis has a base model for each race and gender, but will match your skin color, hair color, and tattoos.

Comment by Arnen

This is the Havoc (DPS) version of the Metamorphosis ability. The appearance the Demon Hunter becomes more demonic, with hooves and wings, as well as an enhanced physique.

It appears that some of the details of the transformation reflect your character customization choices. (This includes your Demon Hunter's hair color and tattoo choice, at the very least -- though note that the tattoos appear to always be bright green, as mine were purple in normal form.) I tested this by changing my Demon Hunter's hair color and tattoo style in the Barber Shop, then re-using Metamorphosis to compare screenshots. I've submitted both screenshots for reference.

If you're looking for the Vengeance (Tank) version of the ability, you can find it here.

Comment by Rezzelyn

Most AoE circles used by other classes are canceled by right-clicking, but "Metamorphosis" is different. The AoE circle can only be cancelled by hitting Esc.